Occupational Hygiene is defined by the International Occupational Hygiene Association in the IOHA Byelaws as 'the discipline of anticipating, recognising, evaluating and controlling health hazards in the working environment with the objective of protecting worker health and well-being and safeguarding the community at large.'

Occupational Hygiene has also been defined as the practice of identifying of hazardous agents, whether chemical, physical or biological , in the workplace that could cause disease or discomfort, evaluating the extent of the risk due to exposure to these hazardous agents, and the control of those risks to prevent ill-health in the long or short term.

The term Industrial Hygiene originated in the USA while in other parts of the world it is known as Occupational Hygiene. In some ways the term occupational is a better description as health risks occur in all places that people work such as offices, shops, hospitals and farms, not just in places regarded as being industrial.

The word hygiene is derived from the name of the Greek goddess of health known as Hygeia. She was the daughter of Asklepios and sister to Panacea. While her father and sister were connected with the treatment of existing disease Hygeia was regarded as being concerned with the preservation of good health and the prevention of disease.